Fuel control



' J. 'DOLZA' July 15, 1958 FUEL CONTROL Filed Sept. 10, 1956 2 Sheets-Sheet 1 INVENTOR. Y dfizzflafza $19M y 5, 1958 J. DOLZA 2,843,100

FUEL CONTROL IN VEN TOR.

m, (/2522 fia/za United States Patent FUEL CONTROL John Dolza, Fenton, Mich., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application September 10, 1956, Serial No. 608,936

3 Claims. (Cl. 123-119) The present invention relates to internal combustion engines and more particularly to charge forming means therefor.

When the load which was formerly driven by an internal combustion engine is overrunning and driving the engine, the fuel in the charge does not perform any useful work and consequently is wasted. In addition, the high induction vacuum resulting from the closed throttle interferes with a complete burning of the charge. Accordingly, numerous attempts have been made to eliminate the fuel from the charge during overrunning conditions. However, so far, these attempts have not been entirely satisfactory as they interfere with the desired performance of the engine and/or they fail to properly stop and restart the fuel flow.

It is now proposed to provide a fuel shut off means that will not interfere with the desired performance of the engine but will be effective to eliminate the fuel flow during those periods where it is desirable to do so. This is to be accomplished by providing pressure responsive means such as a diaphragm that is responsive to the induction vacuum and is operatively interconnected with a normally closed valve in an outlet of the injection pump. During normal operations this valve will be closed and the fuel from the pump will be metered and distributed to the charges for the various engine cylinders. However, in the event that the induction vacuum is in excess of the normal idle vacuum, the pressure responsive means will open the valve and prevent the flow of fuel to the cylinders. It has been found that there are some instances where the induction vacuum is of such magnitude but it is undesirable to disrupt the metered fuel flow. For example, the load may be over'running the engine but the throttle is open sufficiently to allow the engine to develop sufiicient power to assist in maintaining the speed of the engine substantially constant. Under these circumstances it would be undesirable to disrupt the fuel flow. Accordingly, the fuel shut off means may include means responsive to the position of the throttle valve to prevent the means stopping the fuel flow when the throttle valve is at least partially open. In the present instance this is accomplished by providing a vent tube which is located anterior to the throttle valve and having one end thereof interconnected with the vacuum line feeding the induction vacuum signal to the diaphragm chamber. The opposite end terminates adjacent the throttle valve so as to be sealed when the throttle is closed and open when the throttle valve is open. Thus when the throttle ;valveis partially opened the air anterior to the throttle valve may bleed through the vent tube and into the vacuum line. This will prevent the formation of a sufliciently strong vacuum in the diaphragm chamber to open the shut off valve. However, when the throttle valve is substantially closed, the end of the tube will be blocked and, consequently, the diaphragm will be exposed to an unmodified induction vacuum. Thus only in the event the'throttle valve is closed and ,the vacuum becomes sufliciently high willthe diaphragm open the by-pass valve and prevent the injection of any fuel into the charge.

In the two sheets of drawings:

Figure l is an end view, with a portion thereof broken away, of a charge forming unit embodying the present invention.

Figure 2 is a fragmentary cross-sectional view on a slightly enlarged scale of the induction inlet. a

Figure 3 is a cross-sectional view of the fuel metering mechanism employed in the charge forming unit.

Referring to the drawings in more detail the present invention may be adapted for use in a charge forming unit 10 on any suitable engine 12. In the present instance the engine 12 is of the so-called V-type having a cylinder block 14 with a pair of angularly disposed banks 16 of cylinders and an upwardly open space 18 therebetween. The present charge forming unit 10 is attached to and supported by the engine 12 so as to be disposed above the space 18 for delivering the combustible charge for the cylinders.

The present charge forming unit 10 includes an air induction system having a sheet metal shroud 20 that forms an enlarged plenum chamber 22 and an intake manifold 24 that is disposed inside thereof. The shroud 20 has an atmospheric inlet 26 with a filter therein so that the plenum chamber 22 will be filled with filtered air. The intake manifold 24 includes a body 28 having I a chamber therein and a plurality of induction passages 30 that depend therefrom to be secured to the cylinder heads 32 and communicate with the intake passages for charging the engine cylinders. An air meter 34 is mounted on the side of the manifold 24 with a passage extending therethrough so that one end 36 opens into the plenum chamber and the other end 38 communicates with the chamber in the manifold 24. The air meter 34 includes a metering restriction 40 adapted to produce a pressure differential indicative of the air flow and a throttle valve 42 for regulating the air flow. Thus the air meter 34 may draw filtered air from inside of the plenum chamber 22 and deliver throttled air to the intake manifold 24 for distribution to the various cylinders.

The fuel system 44 includes a fuel metering mechanism having a housing 46 that is mounted in the bottom of the plenum chamber 22 so as to be cooled by the circulation of the air therearound. The housing 46 has an inlet 48 in one end thereof interconnected with a source of fuel so as to receive the fuel therefrom. The inlet 48 communicates directly with the fuel bowl 50 and includes a needle valve 52 which is controlled by a float 53 located in the fuel bowl 50. This will be effective to maintain the fuel level in the bowl 50 substantially constant. The injection pump 54 is of the gear type and is driven from the engine 12. It is located in the fuel bowl 50 with the outlet 56 being on top and the inlet 58 being located adjacent the bottom of the bowl 50. Thus the pump 54 will be completely immersed in the fuel in the fuel bowl 50. The outlet 56 from the pump 54 is interconnected with the lower end of a distributing chamber 60 by means of a diagonally extending passage 62. The distributing chamber 60 includes a guide member 64 and a valve housing 66 which has a tapered end 68'that is forced against the lower end of the guide member 64 by a coiled spring 70. The valve housing 66 also includes an axial passage 72 therethrough having a pressure responsive check valve 74 therein. The tension of the spring 76 is set so that the valve 74 will maintain the fuel anterior thereto under at least some predetermined pressure. In the event the fuel pressure is less than this amount the spring 76 will force the check valve 74 closed and prevent the passage of any fuel therethrough. The guide member 64 includes a plurality of spill ports 78 and a reciprocable piston valve 80 that is effective to regulate the flow of fuel through the ports 78. The metered fuel will flow from the distributing chamber 60 through the fuel lines 82 to the various charges by nozzles 84 while the surplus fuel will flow through the spill ports 7 8 and into the linkage chamber 86 from which it will drain back into the fuel bowl 50. It may be seen that the pressure of the fuel in the distributing chamber 60 will be proportional to thefuel to the cylinders and will exert an upward force on the valve 80that will tend to open the spill ports 78 and increase the amount of fuel by-passed.

The housing 46 also includes a diaphragm chamber 88 which is interconnected with the air meter 34 so as to receive the pressure signal indicative of the air flow. One wall of this chamber comprises a flexible diaphragm 90 that is interconnected with a linkage 92 in the linkage chamber 86. The linkage 92 includes a vertical pin'94 that has the upper end thereof attached to the center of the diaphragm 90 and the lower end thereof attached to the joint 96 between the counterweight lever 98 and the control arm 100. The control arm 100 pivots about the end of a ratio arm 101 and bears on the upper end of the piston valve 80. Thus the piston valve 80 will be subject to a downwardly directed force proportional to the air flow.

It may be seen from the foregoing description that when the engine 12 is in operation the air will enter the plenum chamber 22 by way of the filter inlet 26 and will then flow into the air meter 34. At this point the volume of the air will be throttled and the air meter 34 will create a pressure signal indicative of the amount of this air flow. The throttled air will then enter the intake manifold 24 and be distributed to the various cylinders. At the same time the fuel will enter the fuel bowl 50 and the injector pump 54 will force the fuel under pressure into the distributing chamber 60, where it will be divided into two parts, one part being the metered fuel flowing through the injector lines 82 and the other part being the surplus fuel by-passed through the spill ports 78. The upward pressure of the fuel on the piston valve 80 and the downward pressure of the linkage 92 on the piston valve 80 will cause the piston valve 80 to adjust itself until the air and fuel are following in some predetermined proportions.

Although it is necessary to supply a charge of air and fuel to the cylinders for normal operation under some circumstances, for example, when the load is overrunning and driving the engine, it may be desirable to eliminate the fuel flow. Accordingly, a fuel shut off device 102 may be provided for this purpose. It has been found that during the periods when it is desirable to eliminate the fuel flow, the engine 12 will have a considerable speed and the throttle valve 42 will be substantially closed. This produces an unusually high induction vacuum and, in fact, it is unique in that it is higher than even idle vacuum. Accordingly, the shut olf device 102 may be made responsive to the induction vacuum.

The present shut off device 102 includes a valve 104 located in the injector pump outlet 56. This valve 104 is normally retained closed by a spring 106 but is also attached to the center of a diaphragm 108 by a vertical link 110. The chamber 112 for the diaphragm 108 is interconnected with a fitting 114 in the side of the air meter 34 by a vacuum line 116. The fitting 114 communicates with a vent tube 118 and a vacuum passage 120. The vacuum passage 120 opens into a port 122 downstream of the throttle valve 42 so as to sense the induction vacuum while the vent tube 118 projects rearwardly so as to terminate adjacent the throttle valve-42. A button 124 may be provided on the throttle valve 42 so as to engage the open end 126 of the tube 118 and close the same when the throttle valve 42 is substantially closed. When the throttle valve 42 is opened the button 124-will disengage the end 126 of:the tube 118 and allow the air 4 anterior of the throttle valve 42 to bleed through the tube 118 and passage 120 and out of the port 122.

Normally, the spring 106 will retain the valve 104 completely closed and the fuel will be pumped into the distributing chamber 60 so as to be metered and distributed to the charges for the cylinders. However, the

V tension of the spring 106 is adjusted to only balance the force on the diaphragm 108 produced by normal idle vacuum. Thus if the throttle valve 42 is closed and the engine is overrunning to produce a vacuum above the normal idle vacuum, the diaphragm 108 will compress the spring 106 and open the shut off valve 104. This will cause the fuel from the pump outlet 56 to flow directly into the fuel bowl 50. At the same time there will be a suflicient drop in the fuel pressure to cause the check valve 74 to close and prevent the injection of any fuel into the cylinders.

It has been found that under some operating conditions, such as an automotive vehicle coasting down hill with the throttle valve partially open, there may be an exertmely high induction vacuum which would tend to open the shut off ,valve 104. However, since the throttle valve 42 is partially opened, the engine 12 will supply at least a small amount of power which will assist indriving the load. During such conditions the button 124 on the throttle valve 42 will not engage the end 126 ofthe vent tube 118. Thus the air may fiow through the vent tube 118 and into the passage 120. Although this air flow will be very small, it will be large enough to prevent a vacuum in the diaphragm chamber 112 which is in excess of the idle vacuum.

It will be seen that normally the spring 106 will retain the shut olf valve 104 completely closed and the fuel will be delivered to the distributing chamber 60 for metering and distribution to the cylinders. In the event the load overruns the engine 12 and the throttle valve 42 is closed and the induction vacuum becomes high enough, the diaphragm 108 will compress the spring 106 and prevent the injection of any fuel. However, if the throttle valve 42 is opened enough to move the button 124 off of the vent tube 118 and/ or the induction valve decreases, the spring 106 will force the valve 104 closed and again restore the normal metering action.

It is to be understood that, although the invention has been described with specific reference to a particular embodiment thereof, it is not to be so limited since changes and alterations therein may be made which are within the full intended scope of this invention as defined by the appended claims.

I claim:

1. A fuel injection system for injecting fuel into the charge for an internal combustion engine having an induction system with a throttle valve in the inlet thereof for regulating the volume of the charge, said injection system comprising a fuel pump immersed in a fuel bowl and having an outlet for discharging fuel therefrom for distribution to the charges for the engine cylinders, a normally closed by-pass valve operatively interconnected with the outlet of said pump for by-passing fuel discharged therefrom into said bowl, means responsive to the vacuum in said induction system to open said by-pass valve and substantially eliminate the injection of any fuel into the charge whenever said induction vacuum is in excess of some predetermined amount.

2. In a fuel injection system for injecting fuel into the charge for an internal combustion engine having an induction system with a throttle valve in the inlet thereof for regulating the volume of said charge, a fuel pump immersed in a fuel bowl and having an outlet for discharging fuel therefrom for distribution to the charges for the various cylinders of said engine, a normally closed by-pass valve in said outlet, means operatively interconnected with said throttle valve and responsive to the induction vacuum to open said by-pass valve and substantially eliminate the injection of any fuel into the charge by by-passing all of the fuel from said outlet directly into said bowl whenever said induction vacuum is in excess of some predetermined amount and said throttle valve is closed more than some predetermined amount.

3. An inlet to an induction system for an internal combustion engine, said inlet including a throttle valve for regulating the volume of the charge flowing through said induction system and into said engine, a passage opening into said induction system posterior to said throttle valve to sense the amount of vacuum in said induction system and to transmit a signal proportional thereto to a fuel shut off device, a vent tube disposedanterior to said throttle valve with an end thereof terminating adjacent said throttle valve, the other end of said tube communicating with said passage, means on said throttle valve to engage and close said first end of said tube whenever said throttle valve is in the substantially fully closed position, said tube being effective when said throttle valve is not fully closed to bleed air into said passage and thereby reduce the strength of said signal.

References Cited in the file of this patent UNITED STATES PATENTS 1,650,482 Barden Nov. 22, 1927 2,229,851 Hui'ford Jan. 28, 1941 2,453,125 Flint Nov. 9, 1948 

